Method for bleaching teeth

ABSTRACT

The present invention discloses high viscosity sustained release dental compositions, such as tooth bleaching or fluoride compositions, for treating tooth surfaces. For maximum results, an improved dental tray having reservoirs for holding the dental composition adjacent the desired tooth surfaces is preferably used in combination with the sustained release dental composition. The sustained release dental compositions include a high carboxypolymethylene concentration which results in very high viscosity. The high level of carboxypolymethylene makes dilution of the dental compositions from saliva difficult and time consuming so that the compositions stay within the tray reservoirs, thereby providing sustained release. The concentrated carboxypolymethylene adds a unique tackiness to the dental composition which helps retain and seal the soft tray material against the patient&#39;s teeth.

RELATED APPLICATION

This application is a continuation-in-part of copending patentapplication Ser. No. 07/497,934, filed Mar. 22, 1990, in the name of DanE. Fischer and entitled "SUSTAINED RELEASE DENTAL COMPOSITIONS ANDMETHODS FOR TREATING TEETH SURFACES," which is incorporated herein byspecific reference.

BACKGROUND

1. The Field of the Invention

The present invention relates to improved dental compositions andmethods for treating teeth surfaces. More particularly, the presentinvention is directed to high viscosity dental compositions, such astooth bleaching compositions, having significantly improvedeffectiveness and sustained release activity. The dental compositionsmay advantageously be used in combination with a dental tray havingreservoirs for holding the dental composition located adjacent the teethsurfaces to be treated.

2. The Prior Art

Virtually all people desire white or whiter teeth. To achieve this goal,people either have veneers placed over their teeth or have their teethchemically bleached. In the past, patients who desired to have theirteeth bleached had to submit to conventional in-office bleachingtechniques. This usually involved carefully placing a hydrogen peroxidesolution (typically 30% H₂ O₂) on the teeth, protecting the sensitivesoft tissues with a ligated rubber dam, and applying heat to thesolution. Such treatments typically last 30 minutes to 1 hour with from4 to 10 appointments being necessary for a significant change. Only thelabial surface of the 6-8 front teeth is treated.

Since its introduction in early 1989, there has been a growing interestamong the dental profession in home-use tooth bleaching products andmethods. A current representative technique includes: (1) making analginate impression of the patient's teeth; (2) making a stone cast ofthe impression; (3) vacuum forming a tray from the cast, usually fromthin (0.020-0.030 inch) hard transparent material; (4) instructing thepatient to (a) place 2-3 drops of a bleaching solution into each area ofeach tooth to be bleached, (b) place the tray in the mouth, (3)expectorate any excess bleaching solution, (4) change the bleachingsolution every 1 to 2.5 hours, and (5) remove the tray during meals. Afew recommend wearing the tray during the night.

The most commonly used dental bleaching agent is 10% carbamide peroxide(CO(NH₂)₂ H₂ O₂), also called urea hydrogen peroxide, hydrogen peroxidecarbamide, and perhydrol-urea. Carbamide peroxide has been recommendedand prescribed by dental clinicians since the 1960's as an oralantiseptic. Tooth bleaching was a side effect of extended usage. Overthe counter ("OTC") compositions of 10% carbamide peroxide are availableas "Gly-Oxide" by Marion Laboratories and "Proxigel" by Reed andCarnrick.

Positive results using the foregoing technique have been reported. Theeffectiveness depends upon such factors as type and intensity of stain,bleaching agent contact time on teeth, and amount of available activeingredient in the bleaching agent. Because the time commitment for theactual bleaching process takes place outside the dental office, the costfor the procedure is substantially less than conventional in-officebleaching techniques. Moreover, patient discomfort associated withhome-use tooth bleaching techniques both during and after treatment isreportedly less than that associated with conventional in-officebleaching.

Notwithstanding the foregoing advantages, there remain some importantdisadvantages to home-use bleaching products and techniques. Oneimportant disadvantage is that either the bleaching agent must befrequently replaced during the day or the treatment extend for severalweeks or months. Clinical test results indicate that saliva dilution andswallowing of the bleaching agent caused the volume of agent in the trayto diminish rapidly over time, thereby decreasing the amount of activeingredient available for tooth bleaching. Test results show that afterone hour, less than one-half the original volume of bleaching agent waspresent. Thus, existing bleaching agents should be replenished aboutevery hour in order to be effective.

Since current home-use bleaching agents must be frequently replenished,the user necessarily ingests large volumes of the bleaching agent. Inmany cases, ingestion of the bleaching agent causes sore throats. Someresearchers have even suggested that long term repeated ingestion oflarge quantities of carbamide peroxide may be carcinogenic. Therefore,patient ingestion of dental bleaching compositions should be minimized.

Many patient's daytime schedules do not permit them to constantlyreplenish the bleaching agent. In addition, even the suggestion ofperiodically replenishing the bleaching agent during the night would notbe favorably received by most patient's. Because of the inconvenience ofconstantly replacing the dental agent, patient compliance is difficultto maintain, and since patient compliance determines the ultimatesuccess of the treatment, the need to constantly replace the dentalbleaching agent is a major inconvenience which limits the success of thetreatment.

Another disadvantage with current home-use bleaching compositions andtechniques is that it often takes weeks to see an observable result.Although some have reported lightening of teeth in shorter periods oftime, in most cases the home-use bleaching treatment lasts from 4 to 6weeks. Under such circumstances, patients often lose their enthusiasmfor the procedure and often stop complying with the treatment regimen.

From the foregoing, it will be appreciated that what is needed in theart are improved compositions and methods for treating tooth surfaceswhich facilitate patient compliance, so that the ultimate purpose of thetreatment is realized.

Additionally, it would be a significant advancement in the art toprovide sustained release dental compositions for treating toothsurfaces which do not need to be continuously replaced so that patientcompliance is enhanced.

It would be another significant advancement in the art to provide dentalcompositions for treating tooth surfaces which provide a more constantlevel of dental agent in contact with the teeth surfaces rather thanperiodic high and low levels of the dental agent in contact with thepatient's teeth.

It would be an additional advancement in the art to provide dentalcompositions and methods for bleaching a patient's teeth which providenoticeable lightening in a matter of days rather than weeks.

Such dental compositions and methods for treating tooth surfaces aredisclosed and claimed herein.

BRIEF SUMMARY AND OBJECTS OF THE INVENTION

The present invention is directed to high viscosity sustained releasedental compositions, such as tooth bleaching or fluoride compositions,for treating tooth surfaces. An improved dental tray having reservoirsfor holding the dental composition adjacent the desired tooth surfacesis preferably used in combination with the sustained release dentalcomposition.

One currently preferred sustained release dental composition includes adental bleaching agent, such as carbamide peroxide. The concentration ofdental bleaching agent may vary depending upon its reactivity. Forcarbamide peroxide, for example, the currently preferred concentrationrange is from about 3% to about 20%, with a range from about 4% to about15% being most preferred.

The dental bleaching agent is preferably included in a high viscositymatrix material to form the sustained release dental composition.Suitable matrix materials are preferably safe for oral use, do notreadily dissolve in saliva, and do not react with the dental bleachingagent. One currently preferred high viscosity matrix material is asaturated carboxypolymethylene composition. A quantity of base ispreferably added to the carboxypolymethylene composition to adjust thepH to within about 5.0 to about 7.0.

The sustained release bleaching agents within the scope of the presentinvention have such a high viscosity that positive pressure is needed todispense them, gravity is not sufficient. Unlike existing low-viscositybleaching agents, the sustained release bleaching agents cannot bedispensed drop-wise from a bottle. A syringe, squeezable tube, or othersimilar positive pressure dispensing device must be used to dispense thebleaching compositions within the scope of the present invention.

An improved dental tray having reservoirs for holding the dentalcomposition adjacent the desired tooth surfaces is preferably used incombination with the sustained release dental composition. The generalprocess for preparing dental trays is known in the art. For example, analginate impression which registers all teeth surfaces plus gingivalmargin is made and a stone cast is promptly made of the impression. Thereservoirs are prepared by building a layer of rigid material on thestone cast on specific teeth surfaces to be treated. A dental tray isthen vacuum formed from the modified cast using conventional techniques.Once formed, the tray is preferably trimmed barely shy of the gingivalmargin on both buccal and lingual surfaces. The resulting tray providesa perfect fit of the patient's teeth with reservoirs or spaces locatedwhere the rigid material was placed on the stone cast.

The reservoirs may also be creatively built into trays to provideadditional bleaching agent to specific teeth or teeth surfaces whichneed more whitening than others. It has also been found that patientsmay experience less tooth discomfort from tray pressures when using atray with built in reservoirs.

Before commencing a home-use teeth bleaching treatment, it isrecommended that the patient's teeth be clean and that there be norestorations with leaky margins or exposed dentin. If there are largeareas of exposed dentin or if restorations are inadequate, patients candevelop mild to moderately severe pain.

The amount of whitening obtained during tooth bleaching is dependentupon (1) the length of time each day the tray is worn; (2) the number ofdays the tray is worn; and (3) the susceptibility of the teeth to thebleaching agent. For maximum whitening, an accelerated treatment time ofapproximately 18-20 hours per day is recommended. The treatment schedulemay be tailored to each patient's lifestyle or response to thetreatment, but will usually include at least treatment during thepatient's sleep. It has been found that treatment during sleep is themost productive single treatment time of the day since less mouthactivity "pumps" material from the tray.

Recent experimental tests have compared one dental bleaching compositionwithin the scope of the present invention with some commerciallyavailable dental bleaching compositions. All tested bleachingcompositions had the same concentration of active ingredient (10%carbamide peroxide). The tests only examined bleaching effectiveness anddid not consider increased effectiveness resulting from sustainedrelease properties. The experimental results indicate that the presentbleaching composition provides significantly greater effectiveness thanthe other tested bleaching compositions, irrespective of its sustainedrelease properties. It is, therefore, an object of the present inventionto provide highly effective dental bleaching compositions.

An additional object of the present invention is to provide improvedcompositions and methods for treating tooth surfaces which facilitatepatient compliance, so that the ultimate purpose of the treatment isrealized.

Another important object of the present invention is to providesustained release dental composition for treating tooth surfaces whichdo not need to be continuously replaced so that patient compliance isenhanced.

Yet another significant object of the present invention is to providesustained release dental compositions for treating tooth surfaces whichprovide a more constant level of dental agent in contact with the teethsurfaces rather than periodic high and low levels of the dental agent incontact with the patient's teeth thereby providing noticeable lighteningof a patient's teeth in a matter of days rather than weeks.

A further important object of the present invention is to provide animproved dental tray having built in reservoirs for holding dentalcompositions for treating tooth surfaces which enhance the effectivenessof the dental treatment and patient comfort.

These and other objects and features of the present invention willbecome more fully apparent from the description which follows, or may belearned by the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a stone cast of a patient's teeth with arigid coating being applied to selected teeth surfaces.

FIG. 2 is a perspective view of the stone cast of FIG. 1 with a dentaltray formed from the cast and trimmed according to the teachings of thepresent invention.

FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 2.

FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 2.

FIG. 5 is a graph illustrating the results of Example 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As summarized above, the present invention is generally related to highviscosity sustained release dental compositions, such as tooth bleachingor fluoride compositions, for treating tooth surfaces. An improveddental tray having reservoirs for holding the dental compositionadjacent the desired tooth surfaces is preferably used in combinationwith the sustained release dental composition.

One currently preferred sustained release dental composition includes adental bleaching agent, such as carbamide peroxide. The concentration ofdental bleaching agent may vary depending upon its reactivity. Forcarbamide peroxide, for example, the currently preferred concentrationrange is from about 3% to about 20%, with a range from about 4% to about15% being most preferred. In the case of hydrogen peroxide, which ismore reactive than carbamide peroxide, the currently preferredconcentration range is from about 2% to about 10%.

The dental bleaching agent is preferably included in a high viscositymatrix material to form the sustained release dental composition.Suitable matrix materials are preferably safe for oral use, do notreadily dissolve in saliva, and do not react with or inactivate thedental bleaching agent. One currently preferred high viscosity matrixmaterial is a concentrated carboxypolymethylene composition.Carboxypolymethylene is a slightly acidic vinyl polymer with activecarboxyl groups. Suitable carboxypolymethylene compositions may beobtained from B. F. Goodrich Company under the trade name "carbopol".

The normal concentration of various carboxypolymethylene resins inwater, according to the manufacturer, is below about 2%. Somecommercially available dental bleaching compositions contain lowconcentrations of carbopol. Importantly, it has been found that bypreparing saturated carboxypolymethylene compositions having an absoluteconcentration in the range from about 3.5% to about 12%, preferably from4.5% to about 10%, suitable high viscosity, sustained release dentalcompositions may be prepared.

Due to the large quantities of nonaqueous components in the dentalcompositions within the scope of the present invention, the actualconcentration of carboxypolymethylene in the total quantity of water inthe dental composition will preferably be in the range from about 15% toabout 35%, and most preferably from about 20% to about 30%. In somespecial applications where very high concentrations ofcarboxypolymethylene are desired, the concentration ofcarboxypolymethylene in the total quantity of water in the dentalcomposition may even be as great as about 40%.

One currently preferred carboxypolymethylene composition is known asCarbopol 934P. Carbopol 934P is a high purity pharmaceutical grade ofCarbopol 934, having an approximate molecular weight of about 3,000,000.In addition to thickening, suspending, and emulsifying, Carbopol 934Phas been used in dry tablets to impart sustained release properties.Extensive toxicity studies have been conducted on Carbopol 934P, and amaster file has been established with the Food and Drug Administration.It is listed as Carbomer 934P in the National Formulary.

It is believed other carboxypolymethylene resins, such as Carbopol 940,may be substituted for the Carbopol 934P. However, based upon clinicaland laboratory evaluations, Carbopol 940 appears to dilutes faster thanCarbopol 934P. In addition, Carbopol 934P is currently preferred becauseit is obtainable in a pharmaceutical grade. Therefore, Carbopol 934P isa currently preferred carboxypolymethylene composition.

The concentrated carboxypolymethylene compositions within the scope ofthe present invention have a number of important characteristics inaddition to high viscosity. Enough carboxypolymethylene is added to thedental compositions beyond that required to provide high viscosity suchthat a significant quantity of saliva or water is required to lower theviscosity to the point that the dental agent may be diluted and washedout by saliva. Because the high level of carboxypolymethylene makesdilution from saliva difficult and more time consuming, the resultingdental compositions provide a sustained release of the dental agent.

Another important advantage of the concentrated carboxypolymethylenecompositions within the scope of the present invention is that oncontact with saliva, the composition becomes initially firmer. As aresult, a seal around the periphery of the dental tray is formed wherethe composition is in contact with saliva which keeps the remainder ofthe composition in contact with the teeth surfaces entrapped and"sealed" therein. The firmer material at the tray periphery also fillsthe minor discrepancies of the tray-to-tooth fit.

In most cases, high levels of carboxypolymethylene will be preferred sothat the sustained release action of the dental composition will bemaintained over a greater period of time in a high salivating patient.However, in some cases it may be desireable to use lower concentrationsof carboxypolymethylene, relatively speaking, but still higher thantypical concentrations, so that the sustained release action will last ashorter period of time. Thus, by varying the concentration ofcarboxypolymethylene, some control over the period of dental agentactivity may be obtained.

The concentrated carboxypolymethylene composition also has a tackinessor stickiness which retains and seals the thin soft tray materialagainst the teeth thereby preventing migration of the composition out ofthe tray. The tackiness of the composition not only keeps thecomposition within the reservoirs, but also retains the tray against thepatient's teeth, thereby permitting softer, thinner, and more flexibletray materials to be used. It has been found that if too muchcarboxypolymethylene is used, the tackiness can decrease and thecomposition encumbers complete tray insertion.

In order to obtain a concentrated carboxypolymethylene composition, itis recommended that the carboxypolymethylene be mixed with a quantity ofglycerine before attempting to disperse it in water. The glycerineenables the large quantities of carboxypolymethylene to be dispersedeasier in water. It has also been observed that once thecarboxypolymethylene and glycerine are mixed, it is important to quicklydisperse the mixture in the water or else it becomes an unmanageablesolid. It is recommended that the concentration of glycerine in thefinal sustained release dental composition be in the range from about20% to about 70% by weight, and preferably in the range from about 40%to about 60% by weight.

In addition to functioning as a humectant, the glycerine also providessome flavor sweetening enhancement such that a bland flavor isperceived. A few possible substitutes for glycerine includepolypropylene, sorbitol, some polyethylene glycols or other polyols.

It is currently preferred that the amount of water in the sustainedrelease dental composition be in the range from about 10% to about 60%by weight, and preferably in the range form about 15% to about 40% byweight. It will be appreciated that the quantity of water in the totaldental composition may come from different sources. For instance, thedental bleaching agent and base, discussed below, may come as aqueoussolutions.

Because carboxypolymethylene is a polycarboxylic acid, it tends to lowerthe pH of the resulting bleaching composition. It appears, based uponclinical and in vitro testing, that dental compositions with a pH belowabout 5 are able to etch enamel. To avoid etching enamel, it iscurrently preferred to have the pH of the sustained release bleachingcomposition in the range from about 5 to about 7. This is most easilyaccomplished by adding a base to the composition to adjust the pH.Inorganic and organic bases may be used; the use concentrated sodiumhydroxide (50% NaOH) is one currently preferred embodiment. Although itis possible to use lower concentrations of sodium hydroxide or otherbases, such as triethanolamine, there is a risk that the lowerconcentrations may dilute the dental composition and affect itsviscosity or sustained release characteristics.

An important characteristic of the high viscosity, sustained releasedental compositions within the scope of the present invention is thatthe compositions are still observed, from a clinical standpoint, afterabout 3 to 7 hours of normal daytime activity and after about 7 to 10hours of sleep. That is, the sticky, high viscosity dental compositionis still observable in the dental tray after an extended period of time,such as at the end of the night.

Unlike existing low-viscosity bleaching agents which are placeddrop-by-drop into the tray, the sustained release bleaching agentswithin the scope of the present invention have such a high viscositythat they cannot be dispensed dropwise into the tray from a bottle.Positive pressure is needed to expel the sustained release bleachingagents of the present invention, gravity is not sufficient.

One currently preferred method of dispensing the bleaching agent uses asyringe. Squeezable tubes and other similar dispensing devices may alsobe used to dispense the bleaching agent. Upon dispensing, the sustainedrelease bleaching agent is sufficiently viscous that it does not settleor spread when dispensed, but remains as a single extruded strand ofbleaching agent.

It is currently preferred to provide a unit dose of the dental agent ina syringe or similar dispensing device. In this way, the patient canload the precise amount of dental agent onto the dental tray for eachtreatment period. By using such dispensing devices, the dentist is alsoable to monitor and control hoe many doses the patient has received andused.

An improved dental tray having reservoirs for holding the dentalcomposition adjacent the desired tooth surfaces is preferably used incombination with the sustained release dental composition. The generalprocess for preparing dental trays is known in the art. For example, analginate impression which registers all teeth surfaces plus gingivalmargin is made and a stone cast is promptly made of the impression.Excess stone is trimmed away for ease of manipulation and forming of theplastic tray.

Reference is now made to FIGS. 1-4. The present invention modifies knownprocedure by applying a thin coating 10 of rigid material to stone cast12 over the teeth surfaces to be treated. As shown in FIG. 1, coating 10may be conveniently applied using a syringe applicator 14. The coatingmay be also light cured for convenience. Care is taken to ensure thatcoating 10 is kept a distance greater than about 1 mm from gingival line16 and preferably kept from about 11/4 mm to about 11/2 mm from gingivalline 16. The finished coating is preferably about 1/2 mm thick. It isparticularly important when applying the rigid coating material to notcover over incisal edges 18 and occlusal edges 20. These edges shouldcontact the finished tray to prevent vertical movement of the trayduring use which could act as a pump by expressing out the bleachingagent and sucking in saliva.

A dental tray 22 is then vacuum formed from the modified cast usingconventional techniques. Tray 22 is preferably constructed of softtransparent vinyl material having a preformed thickness from about 0.035inch to about 0.06 inch. Soft material is more comfortable for thepatient to wear. Most patient's will find 0.035 inch to be suitable. Itwill be appreciated that the final tray thickness may vary depending onthe technique used to prepare the tray. Patient's suspected of beingbruxers or hard biters may require a 0.06 inch tray material. Of course,patients should be counselled to not eat with trays in place or to bitefirmly into them. In extreme cases, a thicker or harder plastic may benecessary.

Once formed, tray 22 is preferably trimmed barely shy of gingival margin16 on both buccal and lingual surfaces. Enough tray material should beleft to assure that all of the tooth will be covered to within about 1/4mm to about 1/3 mm of the gingival border upon finishing and beveling ofthe tray periphery. It is also important to scallop up and aroundinterdental papilla so that the finished tray does not cover them. Alltray edges are preferably smoothed so that the lip and tongue will notfeel an edge prominence. Slight adjustments to the tray may be made bycarefully heating and stretching the tray material.

From practice, it has been found that patients may experience less toothdiscomfort from tray pressures when using a tray with reservoirs builtinto the tray as described above. It is currently believed this is dueto the fact that the teeth are not held as firmly by the tray, so"orthodontic" pressures experienced by teeth from tray indiscrepanciesare minimized. The use of thin, soft tray materials further minimizesthese "orthodontic" forces, compared to the harder plastics currentlyused in the art.

Reservoirs may also be creatively built into trays to provide additionalbleaching agent to one or more teeth of an arch needing more whiteningthan others or to selected parts of a tooth needing more whitening thanother parts.

To achieve most rapid results, it is recommended to use sustainedrelease bleaching agent within the scope of the present invention incombination with the trays incorporating reservoirs. Nevertheless, ithas been observed that bleaching occurs much more rapidly usingconventional trays with sustained release bleaching compositions of thepresent invention than with existing bleaching agents. In addition, someincrease is effectiveness has also been observed when using existingbleaching agents with trays incorporating reservoirs than withconventional trays without reservoirs.

Before commencing a home-use teeth bleaching treatment, it isrecommended that the patient's teeth be clean of calculus and externalstains. Restorations should be water tight and all dentin, particularlygingival dentin with potential or existing sensitivities, should becovered. It has been observed that exposed root surfaces may experiencesensitivity from sustained release bleaching agent within the scope ofthe present invention. In many cases dentin may be covered with a layerof dentin bonding agent or sealant to prevent this.

Since most patients will want to complete their treatment as soon aspossible, recommended treatment times start at approximately 18-20 hoursa day. Patients are instructed to insert the tray loaded with freshbleaching agent after each meal and before going to bed for most rapidresults. Gum soreness or other patient discomfort has been reported moreoften for such accelerated treatment schedules that go longer than oneto two days.

A second possible treatment schedule is to allow a break-time to occurbetween dinner and bed. This allows the patient to participate inevening social functions without wearing the tray. In addition, oraltissues are allowed to rest during the break-time.

Another recommended treatment schedule, particularly for those where thetreatment may require more than one or two days, is to load and insertthe tray only before bed and after lunch. This gives the teeth and softtissues a rest for approximately two 4-5 hour intervals between the twolonger treatment periods. Potential soreness is most often preventedthis way and treatment time may only be extended 20% to 30% over themore accelerated treatment schedules.

Finally, for those patients who are often in public or those who haveexperienced moderate or greater problems of soreness, it is recommendedthat the tray be worn only at night. During sleep is the most productivesingle treatment time since less mouth activity "pumps" material fromthe tray.

Regardless of which treatment schedule is used, the use of sustainedrelease dental bleaching compositions within the scope of the presentinvention provides a more constant level of bleaching agent adjacent theteeth than existing home-use bleaching systems. Even if patientcompliance with existing home-use dental bleaching systems is such thatfresh bleaching agent is added every hour, there still would be periodichigh and low levels of bleaching agent adjacent the teeth. Since theamount and length of time the active bleaching agent is adjacent theteeth significantly influences the efficiency of the treatment, thesustained release bleaching compositions and methods of the presentinvention represent a significant improvement over existing home-usedental bleaching systems.

If patient instructions are followed, more predictable results areobtained in days rather than weeks. Also, less total volume of bleachingagent is used (from 1/10 to 1/20 the volume of conventional peroxidesolutions). As a result, less bleaching agent is swallowed by thepatient.

At the end of the bleaching treatment, a sustained release fluoridecomposition may optionally be administered to the patient. Forconvenience, the same tray may be used to treat the teeth with fluorideas was used to bleach the teeth. Such fluoride treatment regimens mayinclude 2 to 4 three hour treatments, or 1 or 2 night-time treatments.One typical sustained release fluoride composition within the scope ofthe present invention contains 0.5% sodium fluoride in a high viscositygel.

The following examples set forth various sustained release dentalcompositions within the scope of the present invention. These examplesare intended to be purely exemplary and should not be viewed as limitingthe scope of the present invention.

EXAMPLE 1

A sustained release dental bleaching composition within the scope of thepresent invention was prepared by combining the following ingredients:

    ______________________________________                                        Ingredient        Weight   Weight %                                           ______________________________________                                        Carbamide peroxide                                                                              13.2   gm    10%                                            Water             27.5   gm    21%                                            Glycerine         74.6   gm    57%                                            Carbopol 934P     9.5    gm     7%                                            Sodium hydroxide (50%)                                                                          6.5    gm     5%                                            ______________________________________                                    

The Carbopol 934P was obtained from B.F. Goodrich Company, Cleveland,Ohio. The carbopol was combined with the glycerine and then quicklymixed with the water. The glycerine enables the carbopol to be dispersedin the water. The carbamide peroxide was dissolved in the water beforethe glycerine-carbopol mixture was added to the water. The foregoingcomposition had a percentage of carbopol in water of about 25.7%. Thesodium hydroxide was gradually blended into the homogeneous compositionin order to raise the pH to an acceptable level.

The foregoing procedure produced in a sustained release dental bleachingcomposition which was placed in a dental tray such as that described inconnection with FIGS. 1-4 and worn by a patient for 9 hours. Subsequentexamination of the patient's teeth indicated that the teeth had whitened1-1.5 units on a Vita shade guide and that significant quantities of thesustained release bleaching composition was still observed in theapplication tray.

EXAMPLE 2

A sustained release dental bleaching composition within the scope of thepresent invention was made according to the procedure of Example 1,except that the ingredients were combined in the following amounts:

    ______________________________________                                        Ingredient        Weight  Weight %                                            ______________________________________                                        Carbamide peroxide                                                                              1150    10                                                  Water             2030    18                                                  Glycerine         6660    59                                                  Carbopol 934P      830     7                                                  Sodium hydroxide   650     6                                                  ______________________________________                                    

The foregoing procedure resulted in a sustained release dental bleachingcomposition. The foregoing composition has a percentage of carbopol inwater of about 25.6%. The composition possessed a high viscosity andexcellent sustained release teeth bleaching activity.

EXAMPLE 3

A sustained release dental bleaching composition within the scope of thepresent invention is made according to the procedure of Example 1,except that the ingredients are combined in the following amounts:

    ______________________________________                                        Ingredient       Weight Percent                                               ______________________________________                                        Carbamide peroxide                                                                             20                                                           Water            20                                                           Glycerine        40                                                           Carbopol 934P    12                                                           Sodium hydroxide  8                                                           ______________________________________                                    

The foregoing procedure results in a sustained release dental bleachingcomposition. The foregoing composition has a percentage of carbopol inwater of about 37.5%. The composition possesses a high viscosity andexcellent sustained release teeth bleaching activity.

EXAMPLE 4

A sustained release dental bleaching composition within the scope of thepresent invention is made according to the procedure of Example 1,except that the ingredients are combined in the following amounts:

    ______________________________________                                        Ingredient       Weight Percent                                               ______________________________________                                        Carbamide peroxide                                                                              5                                                           Water            20                                                           Glycerine        60                                                           Carbopol 934P    10                                                           Sodium hydroxide  5                                                           ______________________________________                                    

The foregoing procedure results in a sustained release dental bleachingcomposition. The foregoing composition has a percentage of carbopol inwater of about 33.3%. The composition possesses a high viscosity andexcellent sustained release teeth bleaching activity.

EXAMPLE 5

A sustained release dental bleaching composition within the scope of thepresent invention is made according to the procedure of Example 1,except that the ingredients are combined in the following amounts:

    ______________________________________                                        Ingredient       Weight Percent                                               ______________________________________                                        Carbamide peroxide                                                                             10                                                           Water            40                                                           Glycerine        30                                                           Carbopol 934P    12                                                           Sodium hydroxide  8                                                           ______________________________________                                    

The foregoing procedure results in a sustained release dental bleachingcomposition. The foregoing composition has a percentage of carbopol inwater of about 23.1%. The composition possesses a high viscosity andexcellent sustained release teeth bleaching activity.

EXAMPLE 6

A sustained release dental bleaching composition within the scope of thepresent invention is made according to the procedure of Example 1,except that the ingredients are combined in the following amounts:

    ______________________________________                                        Ingredient       Weight Percent                                               ______________________________________                                        Carbamide peroxide                                                                             18                                                           Water            15                                                           Glycerine        60                                                           Carbopol 934P     4                                                           Sodium hydroxide  3                                                           ______________________________________                                    

The foregoing procedure results in a sustained release dental bleachingcomposition. The foregoing composition has a percentage of carbopol inwater of about 21.1%. The composition possesses a high viscosity andexcellent sustained release teeth bleaching activity.

EXAMPLE 7

A sustained release dental bleaching composition within the scope of thepresent invention is made according to the procedure of Example 1,except that the ingredients are combined in the following amounts:

    ______________________________________                                        Ingredient       Weight Percent                                               ______________________________________                                        Carbamide peroxide                                                                             14                                                           Water            10                                                           Glycerine        70                                                           Carbopol 934P    3.5                                                          Sodium hydroxide 2.5                                                          ______________________________________                                    

The foregoing procedure results in a sustained release dental bleachingcomposition. The foregoing composition has a percentage of carbopol inwater of about 25.9%. The composition possesses a high viscosity andexcellent sustained release teeth bleaching activity.

EXAMPLE 8

A sustained release dental bleaching composition within the scope of thepresent invention is made according to the procedure of Example 1,except that the ingredients are combined in the following amounts:

    ______________________________________                                        Ingredient       Weight Percent                                               ______________________________________                                        Carbamide peroxide                                                                              5                                                           Water            60                                                           Glycerine        20                                                           Carbopol 934P    10                                                           Sodium hydroxide  5                                                           ______________________________________                                    

The foregoing procedure results in a sustained release dental bleachingcomposition. The foregoing composition has a percentage of carbopol inwater of about 14.3%. The composition possesses a high viscosity andexcellent sustained release teeth bleaching activity.

EXAMPLE 9

A sustained release dental fluoride composition within the scope of thepresent invention was prepared by combining the following ingredients:

    ______________________________________                                        Ingredient        Weight   Weight Percent                                     ______________________________________                                        Sodium fluoride   52     gm    1.1%                                           Water             1000   gm    21.5%                                          Glycerine         2980   gm    64.1%                                          Carbopol 934P     380    gm    8.2%                                           Sodium hydroxide (50%)                                                                          238    gm    5.1%                                           ______________________________________                                    

The foregoing ingredients are mixed according to the procedure ofexample 1, except that sodium fluoride is used instead of carbamideperoxide. The fluoride concentration is preferably maintained about 1.1%so that the free fluoride ion concentration is about 0.5%. The foregoingcomposition has a percentage of carbopol in water of about 27.5%. Theforegoing procedure produces a sustained release dental fluoridecomposition suitable for use with a dental tray such as that describedin connection with FIGS. 1-4.

EXAMPLE 10

In this example, the in vitro brightening effect of two commerciallyavailable bleaching agents was measured and compared with the dentalbleaching composition prepared according to the procedure of Example 1.Thirty-six (36) extracted anterior and premolar teeth without caries orrestorations were randomly divided into four (4) groups and mounted. Athermoplastic splint was made for each group. In addition to the dentalbleaching agent of Example 1, Denta-Lite (manufactured by ChallengeProducts, Osage Beach, MO) and Proxigel (manufactured by Reed PCarnrick, Piscataway, (N.J.) were tested. All of bleaching agentscontained 10% carbamide peroxide as the active ingredient. Groups 1-3were treated with the bleaching agents and group 4 was used as a controland bathed in sterile distilled water.

Bleaching agent was placed into a splint and replaced every 3 hoursduring the day and after 8 hours at night. The treatment continued for aperiod of 2 weeks averaging a minimum of 18 hours of bleaching per day.All teeth and splints were brushed and rinsed with water beforereplacing bleaching agents.

Measurements were taken using a Pentax photo spot meter, measuringbrightness changes occurring at intervals of 24 hours, 72 hours, 7 days,and 14 days. The photo spot meter was equipped with an analog meter andthe ability to read in 0.1 value variations. The meter was attached to ameasuring apparatus which reflected two light sources at a 60 degreedeflection angle toward the crown of the tooth being measured. Arheostat controlled the light sources to allow a constant emittanceduring each measurement. The data were analyzed using a 2-way ANOVA andDuncan's multiple range test.

Photographs were taken before, at 72 hours, and at 14 days followingbleaching. A 35 mm single reflex camera with a macro lens and a 2×diopter was used for all photography.

The results of this Example are reported in Table 1 and illustratedgraphically in FIG. 5. They indicate that the dental bleachingcomposition within the scope of the present invention is over 50% moreeffective than the two commercially available dental bleaching agentshaving the same concentration of active ingredient. In fact, thebleaching agent of Example 1 provided greater whitening in just 3 daysof treatment than the other bleaching agents did after two weeks oftreatment.

It is important to recognize that the results of this Example to notaddress the impact of saliva on the effectiveness of the dentalbleaching agents. The sustained release characteristics of the dentalbleaching agent within the scope of the present invention were notaddressed by this Example. Therefore, the effectiveness of the presentinvention can be expected to be even greater than the prior artbleaching agents when the sustained release activity is considered.

                  TABLE 1                                                         ______________________________________                                        Bleaching Effect of 10% Carbamide Peroxide                                    Value Changes: Means and standard deviations                                  Bleaching                                                                     Agent    No.    24 Hrs.  72 Hrs.                                                                              7 Days 14 Days                                ______________________________________                                        Water    9      0        0      0      0                                      Example 1                                                                              9      .34 (.06)                                                                              .56 (.08)                                                                            .60 (.09)                                                                            .67 (.13)                              Denta-Lite                                                                             9      .22 (.08)                                                                              .35 (.11)                                                                            .38 (.10)                                                                            .48 (.13)                              Proxigel 9      .22 (.07)                                                                              .33 (.12)                                                                            .34 (.11)                                                                            .40 (.10)                              ______________________________________                                    

Although much of the foregoing discussion has focused on sustainedrelease dental bleaching or fluoride compositions, it will beappreciated that other dental compositions, whether sustained release ornot, may also be prepared and used within the scope of the presentinvention. For instance, anticariogenic agents such as chlorhexidinegluconate and antimicrobial agents for treating periodontal pockets suchas tetracycline may be incorporated into sustained release compositions.When the such dental compositions are for treating soft tissues, thepreferred tray design may need to be altered so that the tray overlapsthe patient's gums.

In some cases, the dental agents may be used without a dental tray. Forexample, a sustained release dental composition having an antimicrobialagent may be expressed directly into periodontal pockets. In suchcompositions, it would be preferred to maximize the carboxypolymethyleneconcentration so that the effects of saliva dilution are minimized. Inaddition, mucosal adhesive materials may be added to the composition tofurther assist in retaining the composition within the periodontalpocket. Sustained release action may last from hours to days, dependingon the patient's oral and salival activity.

From the foregoing, it will be appreciated the present inventionprovides improved compositions and methods for treating tooth surfaceswhich facilitate patient compliance, so that the ultimate purpose of thetreatment is realized.

Additionally, it will be appreciated that the present invention furtherprovides sustained release dental compositions for treating toothsurfaces which do not need to be continuously replaced so that patientcompliance is enhanced. The present invention also provides sustainedrelease dental compositions for treating tooth surfaces which permit amore constant level of the dental agent to be in contact with the teethsurfaces rather than periodic high and low levels of the dental agent incontact with the patient's teeth.

It will be further appreciated that the present invention providesdental compositions and methods for bleaching a patient's teeth whichprovide noticeable lightening in a matter of days rather than weeks.

In addition, it will be appreciated that the present invention providesan improved dental tray having built in reservoirs for holding dentalcompositions for treating tooth surfaces which enhance the effectivenessof the dental treatment and patient comfort.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. A method for bleaching a patient's teeth comprising:(a)obtaining a dental tray configured to cover a patient's teeth surfacesto be bleached and configured to hold a quantity of dental bleachingcomposition; (b) placing a quantity of dental bleaching compositionwithin the dental tray, said dental bleaching composition comprising:aquantity of dental bleaching agent capable of bleaching vital toothsurfaces in contact with said dental bleaching agent; and a matrixmaterial into which the dental bleaching agent is dispersed, said matrixmaterial including carboxypolymethylene in the range from about 3.5% toabout 12% by weight of the dental bleaching composition; (c) positioningthe dental tray over the patient's teeth surfaces such that a portion ofthe dental bleaching composition is in contact with the patient's teethsurfaces to be bleached; (d) allowing the dental tray to remainpositioned over the patient's teeth surfaces; and (e) removing thedental tray from the patient's teeth.
 2. A method for bleaching apatient's teeth as defined in claim 1, wherein the step of obtaining adental tray further comprises obtaining a dental tray constructed withreservoirs for holding additional dental bleaching composition such thatwhen the dental tray is positioned over the patient's teeth surfaces,the additional dental bleaching composition within the reservoirs is incontact with the patient's teeth surfaces to be bleached.
 3. A methodfor bleaching a patient's teeth as defined in claim 1, furthercomprising the step of repeating steps (b) through (e).
 4. A method forbleaching a patient's teeth as defined in claim 1, wherein the quantityof dental bleaching composition placed within the dental tray includes amatrix material comprising carboxypolymethylene in the range from about4.5% to about 10% by weight of the dental bleaching composition.
 5. Amethod for bleaching a patient's teeth as defined in claim 1, whereinthe quantity of dental bleaching composition placed within the dentaltray includes a matrix material comprising carboxypolymethylene in therange from about 6% to about 8% by weight of the dental bleachingcomposition.
 6. A method for bleaching a patient's teeth as defined inclaim 1, wherein the quantity of dental bleaching composition placedwithin the dental tray includes a matrix material comprisingcarboxypolymethylene in the range from about 15% to about 35% by weightof the total quantity of water in the total dental bleachingcomposition.
 7. A method for bleaching a patient's teeth as defined inclaim 1, wherein the quantity of dental bleaching composition placedwithin the dental tray includes a matrix material comprisingcarboxypolymethylene in the range from about 20% to about 30% by weightof the total quantity of water in the total dental bleachingcomposition.
 8. A method for bleaching a patient's teeth as defined inclaim 1, wherein the quantity of dental bleaching composition placedwithin the dental tray includes a carbamide peroxide as the dentalbleaching agent in the range from about 3% to about 20% by weight of thedental bleaching composition.
 9. A method for bleaching a patient'steeth as defined in claim 1, wherein the quantity of dental bleachingcomposition placed within the dental tray includes a carbamide peroxideas the dental bleaching agent in the range from about 4% to about 15% byweight of the dental bleaching composition.
 10. A method for bleaching apatient's teeth as defined in claim 1, wherein the dental tray remainspositioned over a patient's teeth for a period of time greater thanabout 3 hours and wherein the dental bleaching composition remainsactive while the dental tray is positioned over the patient's teethsurfaces.
 11. A method for bleaching a patient's teeth as defined inclaim 1, wherein the dental tray remains positioned over a patient'steeth for a period of time greater than about 5 hours and wherein thedental bleaching composition remains active while the dental tray ispositioned over the patient's teeth surfaces.
 12. A method for bleachinga patient's teeth as defined in claim 1, wherein the dental tray remainspositioned over a patient's teeth for a period of time greater thanabout 8 hours and wherein the dental bleaching composition remainsactive while the dental tray is positioned over the patient's teethsurfaces.
 13. A method for bleaching a patient's teeth as defined inclaim 1, wherein the quantity of dental bleaching composition placedwithin the dental tray is sufficiently tacky to retain the dental traypositioned against the patient's teeth surfaces.
 14. A method forbleaching a patient's teeth as defined in claim 1, wherein the quantityof dental bleaching composition placed within the dental tray becomesfirmer upon contact with saliva.
 15. A method for bleaching a patient'steeth as defined in claim 1, wherein during the positioning step, aportion of the dental bleaching composition extends to the edge of thedental tray and forms a seal upon contact with saliva.